<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            list-style: none;
        }
        
        .nav {
            width: 900px;
            height: 60px;
            background-color: black;
            margin: 0 auto;
        }
        
        .nav li {
            width: 100px;
            height: 60px;
            /*border: 1px solid yellow;*/
            float: left;
            position: relative;
            overflow: hidden;
        }
        
        .nav a {
            position: absolute;
            width: 100%;
            height: 100%;
            font-size: 24px;
            color: blue;
            text-align: center;
            line-height: 60px;
            text-decoration: none;
            z-index: 2;
        }
        
        .nav span {
            position: absolute;
            width: 100%;
            height: 100%;
            background-color: yellow;
            top: 60px;
        }
    </style>
    <script src="../../js/jquery-3.1.0.js"></script>
    <script>
        $(function() {
            $(".nav li").mouseenter(function() {
                $(this).children("span").stop().animate({
                    top: 0
                });
            }).mouseleave(function() {
                $(this).children("span").stop().animate({
                    top: 60
                });
            });
        });
    </script>
</head>

<body>
    <div class="nav">
        <ul>
            <li>
                <a href="javascript:void(0);">导航1</a>
                <span></span>
            </li>
            <li><a href="javascript:void(0);">导航2</a><span></span></li>
            <li><a href="javascript:void(0);">导航3</a><span></span></li>
            <li><a href="javascript:void(0);">导航4</a><span></span></li>
            <li><a href="javascript:void(0);">导航5</a><span></span></li>
            <li><a href="javascript:void(0);">导航6</a><span></span></li>
            <li><a href="javascript:void(0);">导航7</a><span></span></li>
            <li><a href="javascript:void(0);">导航8</a><span></span></li>
            <li><a href="javascript:void(0);">导航9</a><span></span></li>
        </ul>
    </div>
</body>

</html>